The present invention relates to a microwave line structure.
More particularly, it relates to a microwave line structure which has a first conducting track applied onto a substrate, a second conducting track supported on posts and extending at a distance above the first conducting track, and a coplanar line arranged on the substrate and coupled to a microstrip line extending between the conducting tracks of a coplanar line.
It is known to use planar lines, for example in the form of microstrips or coplanar lines for circuits in microwave technology. As described, for example, in the book "Streifenleitungen" [Striplines] by Geschwinde and Krank, Winterische Verlagshandlung, 1960, pages 1 to 4, microstrips consist of two planar lines applied onto opposite sides of a substrate. Coplanar lines have two or three lines extending next to one another on one substrate side. A microwave line structure as described at the outset, is described in German Patent Specification 40 32 260. In this case a microstrip line is arranged between the two conducting tracks of a coplanar line.
In radio-frequency technology, the transition from an asymmetrical line, for example a coaxial line, to a symmetrical line, for example a two-wire line, is effected using a balancing element which is also referred to in the technical literature by the name balun. Exemplary embodiments for such balancing elements are specified in the book Zinke, Brunswick: "Lehrbuch der Hochfrequenztechnik" [Textbook on Radio-Frequency Technology] Volume 1, page 104.
In microwave technology, increasing use is being made of integrated circuits, so-called monolithic microwave integrated circuits MMIC.